JP3311416B2 - Battery retention time prediction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for estimating the retention time of a battery, and more particularly to an apparatus for estimating the retention time of a secondary battery incorporated in an uninterruptible power supply or the like.

[0002]

2. Description of the Related Art If a power failure occurs during use of an information device such as a personal computer, office computer, word processor, workstation or the like and the power is turned off, data being created or the like will be lost or even stored in memory. There is a risk of destroying certain data. Therefore, the uninterruptible power supply (UP
S), the power is supplied from the uninterruptible power supply for a certain period of time in the event of a power outage, thereby enabling continuous use, and by performing predetermined data storage and other termination processing as necessary, the above problem is solved. Can be prevented from occurring.

In recent years, office automation,
In some cases, small control computers are distributed for factory automation. For each computer, the above-mentioned UPS is installed to protect the system and perform predetermined functions even during a power failure. ing.

A small-capacity UPS installed for each information device has a built-in secondary battery for backup which does not require maintenance, and normally supplies current from a commercial power supply to the secondary battery. The power is also supplied to the load, and at the time of a power failure, a switch is switched to continuously supply power to the load by discharging from the secondary battery.

[0005] By the way, at the time of actual power outage, the retention time of how long the backup (power supply from the UPS) lasts is an important factor in determining the processing to be performed at present. That is, when the apparatus is to be used for a relatively long time, it can be continuously used. However, if the continuous use is performed as it is when the holding time is short, the power supply from the UPS is lost during the use, and the same problem as described above may occur.

Therefore, conventionally, at the design stage of such a device, the holding time when the secondary battery is fully charged is calculated from the assumption of the capacity and load of the secondary battery, and the calculated holding time is used as a reference holding time for the user. In some cases, the progress of discharge is detected by presenting or measuring and monitoring the terminal voltage during backup.

[0007]

However, in the above-mentioned conventional device, the load at the time of backup is not always exactly as designed, and the discharge capacity of the battery changes due to temperature and the like. The remaining holding time is only a guide and the remaining holding time under the actual use condition cannot be known. On the other hand, although the discharge situation can be detected from the terminal voltage, the discharge characteristics do not change linearly but the voltage suddenly drops at a certain time, so how many minutes can the backup actually be performed after the discharge situation? It is difficult to determine. Therefore,
In the conventional system, various devices are used because of the fear that the backup may stop suddenly at all times. Even in such a case, it is necessary to end the process immediately after the power failure to secure data and the like, which is inconvenient.

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and an object of the present invention is to accurately predict the remaining time that can be backed up, and to ensure that the users of various devices that receive the backup have appropriate It is an object of the present invention to provide a battery retention time predicting device capable of performing various processes and improving reliability.

[0009]

In order to achieve the above object, a battery retention time predicting apparatus according to the present invention comprises a means for measuring an ambient temperature of a battery and a means for integrating the power.
And a means for measuring power discharged from the battery;
Means for generating a holding time for the terminal voltage of the battery to maintain a predetermined value or more based on the ambient temperature, the output power, and the integrated power detected by each of the measuring means.

[0010]

By measuring the power discharged from the battery, the state of the load under the actual use condition is detected. And the ambient temperature, which greatly affects the discharge characteristics of the battery,
Such actual load power (substantially equal to battery discharge power)
And the holding time is predicted from the integrated value of the power . Therefore, the user, etc. can know the retention time under the usage conditions at that time, and can continue working with peace of mind, and if the remaining time is short, perform appropriate processing to ensure data protection etc. Can be

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a battery retention time estimating apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. FIG.
Shows an example in which an embodiment of the retention time prediction device according to the present invention is mounted on a floating charge type UPS. As shown in the figure, the output of the commercial power supply 1 is connected in parallel to the changeover switch 2 and the charger 3, and the output of the commercial power supply 1 is supplied to the load 4 via the changeover switch 2 in normal times. On the other hand, the charger 3 performs floating charging on the battery 5 while converting AC output from the commercial power supply 1 into DC. As a result, even if the battery 5 self-discharges, it is constantly charged with a weak current, and the battery 5 is always in a fully charged state in principle. The battery 5 is connected to the inverter 6
Is connected to the changeover switch 2 via a switch. When the power outage occurs, the changeover switch 2 is switched so that the battery 5
, And the power is continuously supplied to the load 4 via the inverter 6 and the changeover switch 3. Note that such a configuration is basically the same as that of a conventional UPS, and thus a detailed description thereof is omitted.

Here, in the holding time estimating apparatus according to the present embodiment, first, the sensor 10 is installed near the battery 5.
The sensor 10 includes a sensor unit that measures an ambient temperature of the battery 5 and a terminal voltage and an output current of the battery 5 for obtaining a discharge power of the battery. And
The measurement data detected by each sensor unit is sent to the processing unit 11, where the holding time is predicted by fuzzy inference and the remaining time is calculated.
The display unit 12 is configured to transmit the estimated remaining backup time to the display unit 12 made of D or the like to notify the user. The remaining time may be sent to a device such as a computer connected to the display instead of or in addition to the display, and the computer may perform an appropriate process according to the remaining time. In particular, it is useful in the case of a computer (control device) used for factory automation or the like.

That is, the predicted holding time calculated by the present invention is based on how much the battery has when the power failure occurs and the load state at the time of the power failure continues (when the voltage exceeds the predetermined voltage value). Time that can be retained)
The discharge characteristics of the battery generally have a curve as shown in FIG. 2. In the case of batteries having the same level of discharge capacity, they are almost the same if the load power and the ambient temperature are constant. In other words, if the power or the temperature is different, the characteristics are different. If the load power or the ambient temperature is changed after the holding time is predicted, the holding time at that time is changed from the prediction result. Therefore, in the present embodiment, the power and the temperature are measured using the sensor 10 as described above, and prediction is performed based on the measured power and temperature.

Here, as shown in FIG. 1B, the processing unit 11 first calculates the ambient temperature and the load power measured by the sensor 10, that is, the discharge power (voltage × current) of the battery 5 to predict the holding time. The data is input to the unit 11a, where fuzzy inference is performed, and the holding time when the device is continuously used under the condition at the time of the power failure is predicted. In this example, a simplified fuzzy inference device whose conclusion part is a singleton is used. Specifically, as an example, a membership function as shown in FIGS. 3A and 3B and a membership function as shown in FIG. Inference processing is performed using the rule shown in FIG.

Further, the predicted holding time obtained in this manner is a value when the battery is fully charged, and is actually in the middle of charging (the charging rate is less than 1). Since there is already an amount of power used (discharged) by the backup before the calculation, the predicted holding time is corrected in consideration of the amount of charge (charge rate and amount of discharge). Specifically, it is obtained by the following equation.

[0016]

[Equation 1] Predicted holding time after correction = Predicted holding time by fuzzy inference−Correction amount Correction amount = (Nominal battery capacity × (1−Charging rate) + Power integration)
However, the nominal capacity of the battery in the above equation is the integral value of “nominal voltage (12 V in this example) × output current”. Similarly, the power integration is based on “discharge after starting discharge”. It is the integral value of “current × terminal voltage”. The charging rate is a value obtained by dividing a value obtained by time-integrating a charging current at the time of charging the battery 5 × a terminal voltage by the above-mentioned battery nominal capacity. The power used for inference is calculated when the holding time is estimated. “Output current × terminal voltage” immediately after the start of discharge used.

Then, the final predicted time obtained in this way is preset in the next-stage timer 11b. This timer 11b is decremented every second and the timer 1b
The current value of 1b is output to the display unit 12 as the remaining time that can be backed up.

Further, the holding time estimating unit 11 in this embodiment
In a, the power used for the above inference (“output current × output voltage” immediately after the start of discharge) is stored in a buffer or the like.
This is compared with the power during backup sent from the sensor 10 to monitor the presence or absence of a load change. If there is a load change, the inference processing is again performed to predict a holding time according to the changed load, and to the timer 11b. Is to be reset. That is, in this example, the means for detecting a change in load is also used for the holding time prediction unit 11a.

When the battery 5 is deteriorated, the discharge characteristic curve decreases in a relatively short time, that is, the holding time is shorter than that of a new battery. Therefore, the UPS may stop before the value of the timer 11b becomes zero. Therefore, in this example, the change in the terminal voltage during the actual backup is monitored, and the predicted holding time is corrected as necessary.

That is, first, the holding time prediction unit 11a
And the ambient temperature and the load power obtained by the above measurement are input to the determination unit 11c, and a fuzzy inference is performed to the timer 1
A standard curve (reference voltage at each time) of the terminal voltage drop until the output of 1b becomes zero is obtained.

In this embodiment, a standard curve as shown by a broken line in FIG. 4 is created by obtaining each reference voltage at each fine time interval and connecting the obtained many reference voltages. In this example, in principle, every minute (1 minute before the reference voltage, 2
Minute reference voltage ...). However, since the amount of change in the voltage drop at the beginning of the discharge is relatively small, the interval is increased from the middle (for example, 5 minutes or 1 minute before 10 minutes or more).
0 minute intervals, etc.).

The specific fuzzy knowledge for performing the inference is based on the membership function of the condition part (temperature, power), which is used when calculating the predicted holding time, as shown in FIG.
The same function as the one shown in (B) is used, and an example of the rule is as shown in FIG. In this example, the rule for obtaining the reference voltage one minute before the end of the discharge (timer output = 0) is shown. However, although not specifically shown, the rule for each time is created and stored as described above. Use what was done. Note that the rules shown are for the battery 5 having a terminal voltage of 12V.

Next, each of the obtained reference voltages (standard curves) is inputted to the next stage voltage drop judging section 11d, and the judgment section 11d obtains the output (remaining time) of the timer 11b and the sensor 10 The terminal voltage of the battery is input. The voltage drop determination unit 11d obtains the current reference voltage from the current remaining time provided by the timer 11b and the standard curve, and compares the reference voltage with the actual terminal voltage. If the actual terminal voltage is lower, it is considered that the battery has deteriorated. Therefore, the remaining time based on the current terminal voltage (which is shorter than the initially obtained time) is determined by performing correction, and Is set in the timer 11b as a correction value. And
The timer 11b subtracts from the reset time and outputs the remaining time.

In this correction process, a point on the standard curve equal to the current terminal voltage is detected, and the remaining time at that point is determined as a correction value. That is, for example, if the change in the terminal voltage of the actual battery is as shown by the solid line in FIG. 4, the terminal voltage v1 at a certain time t1 is lower than the reference voltage v0 at the same time, and thus it is determined that the battery is deteriorated. Then, the process proceeds to the correction process. Then, the terminal voltage v1 is translated and intersected with the standard curve, that is, the position of the terminal voltage v1 on the standard curve is obtained, and the time (remaining time) t2 at that time is set in the timer 11b. When the remaining time is shortened due to the correction process, a predetermined message is displayed on the display unit 12 or the remaining time is blinked, so that the remaining time is reduced for the user. It is designed to teach. Alternatively, a warning by sound such as a buzzer may be issued instead of or in addition to the display.

When the actual terminal voltage is higher than the above-mentioned reference voltage, the actual remaining backup time is longer than the output of the timer. In this case, no correction is made. However, a correction process may of course be performed.

As shown in FIG. 2, immediately after the start of discharge due to the occurrence of a power failure, the terminal voltage of the battery 5 may drop temporarily. Therefore, when such a phenomenon occurs, there is a possibility that the phenomenon is erroneously determined as battery deterioration. Therefore, in a region where such a phenomenon may occur, the deterioration determination is not performed. That is, the instantaneous power is obtained from the product of the output current and the terminal voltage, and the power amount is obtained by integrating the instantaneous power. Then, the terminal voltage is ignored (the deterioration determination or the correction process is not performed) until the power amount reaches a certain value. In the process, for example, the load power that is constantly input in the deterioration determination voltage determination unit 11c is integrated, and the integrated value is compared with a predetermined threshold value. The reference curve is not sent to the voltage drop judging unit until it reaches the predetermined integration value (or the terminal voltage input to the voltage drop judging unit 11d is 0 V).
Is compared to the reference voltage and becomes higher than the reference voltage and no correction processing is performed
It is executed by doing so. That is, in this example,
Means for detecting that predetermined energy has been discharged after the start of discharging of the battery is built in the deterioration determination voltage determination unit 11c. Further, means for detecting the deterioration of the voltage and correcting the holding time is configured by the deterioration determination voltage determination unit 11c and the voltage decrease determination unit 11d.

Next, the operation of the above embodiment will be described with reference to the flowchart shown in FIG. That is, when the occurrence of a power failure is detected, the changeover switch 2 is switched to supply power from the battery 5 to the load 4. Then, the ambient temperature and the output current / voltage (load power) of the battery at this time are measured (S101, 102). Next, the measured various data are input to the holding time estimating unit 11a in the processing unit 11 to perform fuzzy inference, perform correction based on the charging rate and the discharge amount, and calculate the estimated holding time (S103, 10).
4).

Then, the prediction result is set in the timer 11b, and the timer is started. Then, the remaining time, which is the timer output, is always displayed (S105, S10).
6). At this time, the holding time prediction unit 11a compares the input load power with the load power used for inference for the holding time prediction to determine whether there is a load change (S10).
7) If there is a change, the process returns to step 102 and prediction is performed again. On the other hand, if there is no fluctuation, the process is continued as it is (subtraction of the timer), the process proceeds to the next step, and the deterioration determination voltage determination unit 11c determines whether the power amount from the start of discharge exceeds a certain value (S108). . Then, the processing in the loop of steps 106 to 108 is repeatedly performed until it exceeds.

On the other hand, if the amount of power exceeds a certain value, the process proceeds to step 109 and thereafter, the terminal voltage is monitored by the voltage drop determining unit 11d, and the process proceeds to a correction processing loop for remaining time due to battery deterioration. That is, if there is no load change, it is determined whether or not the terminal voltage is equal to or higher than a predetermined reference voltage. If it is, the display is continued until the timer reaches zero. Of the battery due to overdischarge is suppressed (S109 to S113). On the other hand, if there is a load change, the process returns to step 102 in the same manner as described above, and fuzzy inference is performed again to reset the holding time. When the terminal voltage becomes lower than the reference voltage, the timer value is corrected (S114), and the process returns to step 105 to restart the timer when the timer is reset.

[0030]

As described above, in the battery retention time predicting apparatus according to the present invention, the retention time according to the actual use condition is predicted from the load power , the temperature condition, and the integrated value of the power. Therefore, the user of the device driven by the battery can perform the operation with peace of mind. And since the retention time (remaining time) can be known in such a manner, the battery can be discharged to its full capacity and the backup process can be performed. Therefore, there is no need to use a battery having a capacity larger than necessary.
A device mounted with a battery such as an uninterruptible power supply can be downsized.

When a means for correcting the holding time and / or a means for detecting a change in the load are provided, it is detected that the battery is deteriorated and the predicted value is corrected, or the load is changed. In this case, re-estimation can be performed, so that the remaining time according to the use situation can always be obtained, and the remaining time that can be backed up can be more accurately estimated. Therefore, a user of various devices that receive the backup can perform an appropriate process. further,
In the case where the means for detecting the discharge energy amount of the battery is provided, it is not affected by the transient fluctuation of the output voltage at the initial stage of the discharge of the battery, so that it is possible to accurately predict (correct) the holding time.

[Brief description of the drawings]

FIG. 1 is a diagram showing a preferred embodiment of a retention time prediction device according to the present invention and an example of a UPS mounting the same.

FIG. 2 is a diagram illustrating an example of a discharge characteristic of a battery.

FIG. 3 is a diagram showing fuzzy knowledge for performing holding time prediction.

FIG. 4 is a diagram for explaining a predicted terminal voltage (standard curve) with respect to an elapsed time of a battery and a correction of a holding time accompanying deterioration of the battery.

FIG. 5 is a diagram showing an example of a fuzzy rule for obtaining a standard curve.

FIG. 6 is a flowchart illustrating the operation of the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Commercial power supply 2 Changeover switch 3 Charger 4 Load 5 Battery 6 Inverter 10 Sensor 11 Processing part 11a Holding time prediction part 11b Timer 11c Deterioration determination voltage determination part 11d Voltage drop determination part 12 Display part

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yasufumi Fukao 1st, Nishi-no-Sho, Inobamaba-cho, Kichijo-in, Minami-ku, Kyoto-shi, Kyoto Inside Nippon Battery Co., Ltd. (56) References A) JP-A-2-3055591 (JP, A) JP-A-57-200874 (JP, A) JP-A-2-26207 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) ) G01R 31/36

Claims (5)

(57) [Claims] 1. A means for measuring an ambient temperature of a battery, a means for measuring power discharged from the battery, a means for integrating the power, and an ambient temperature and output power detected by each of the measuring means. And a means for generating a holding time for maintaining the terminal voltage of the battery at a predetermined value or more based on the integrated power. 2. The apparatus according to claim 1, further comprising means for subtracting the elapsed time from the start of discharging of the battery from the holding time to calculate and output a remaining holding time. 3. The battery according to claim 1, further comprising means for detecting deterioration of the battery from the terminal voltage of the battery, and correcting the obtained holding time at least when the battery is deteriorated. Holding time prediction device. 4. A method according to claim 1, further comprising means for detecting that a predetermined amount of energy has been discharged after the start of discharging of the battery, and after the detection, deterioration detection by means for correcting the holding time and correction associated therewith are started. Item 4. A battery retention time prediction device according to item 3. 5. The apparatus according to claim 1, further comprising means for detecting a change in load, wherein when the change is detected, the means for generating the holding time is restarted to predict and correct the holding time again. 5. The battery retention time prediction device according to any one of items 4 to 4.